English Grammar: Ability Modals Quiz

Ability

• Can/Can't + Infinitive: Expresses general ability now or decisions made now about the future. Examples: "I can run a kilometer in four minutes," "We can meet at the gym tomorrow."
• Could + Infinitive: Expresses ability in the past, hypothetical situations (present, future, generally). Examples: "I could do fifty press-ups with one hand when I was younger," "I wish I could quit smoking."
• Be able to + Infinitive: Expresses ability, often in other tenses. Examples: "I'd love to be able to fit into these jeans again," "I'll be able to leave hospital in a few weeks."
• Was/Were able to + Infinitive/Managed to + Infinitive/Succeeded in -ing: Expresses ability on a specific occasion in the past. Examples: "I was able to find some information this morning," "I managed to convince my brother to watch a horror film last night."
• Could + Perfect Infinitive: Expresses ability in past hypothetical situations. Example: "I could have roasted the potatoes, but I decided that boiling them was healthier."

Permission

• May + Infinitive (+polite): Asking for permission. Example: "May I see the doctor, please?"
• Could + Infinitive (polite): Asking for permission (more polite than "can"). Example: "Could I have some water, please?"
• Can + Infinitive: Asking for permission. Example: "Can I go to the toilet, please?"
• May + Infinitive (polite): Giving permission. Example: "You may send the fax when you like."
• Can + Infinitive: Giving permission. Example: "She can finish the homework later."
• Be allowed to + Infinitive: Permission on one occasion in the past. Example: "He was allowed to post a video on the site yesterday."

Advice

• Should / Ought to / Had better + Infinitive: Expressing advice. Examples: "Liam should / ought to / had better watch less TV," "what should I wear for a job interview?" "Had better" is stronger than "should" or "ought to."

Criticism

• Should / Ought to + Perfect Infinitive: Criticizing a past behavior. Example: "He should / ought to have made more of an effort with his diet."

Obligation and Necessity

• Must / Have to / Need to + Infinitive: Expresses obligation or necessity in the present. Examples: "All visitors must turn off their mobile phones," "You have to press 'send'." "Do I need to take this medicine?"
• Had to + Infinitive: Expresses obligation or necessity in the past. Example: "I had to take the pills three times a day for two weeks."
• Will have to / Will need to + Infinitive: Expresses obligation or necessity in the future. Example: "I will need to be more careful about what you eat in the future."

Lack of Obligation and Necessity

• Don't have to / Don't need to / Needn't / There's no need to + Infinitive: Expressing lack of obligation or necessity in the present. Example:"You needn't pick up that prescription from the chemist as I'll get it while I'm in town."
• Didn't have to / Didn't need to + Infinitive: Expressing lack of obligation or necessity in the past. Example: "You didn't have to go to the doctor because I suddenly felt better."
• Won't have to / Won't need to + Infinitive: Expressing lack of obligation or necessity in the future. Example: "I won't need to drive to school in summer."
• Needn't + Perfect Infinitive: Expressed unnecessary past action. Example: "I needn't have bought red paint because we didn't use it."

Certainty

• Must / Can't / Couldn't + Infinitive: Expressing certainty about now or generally. Examples: "The phone is ringing - it must be Simon," "This letter can't / couldn't be from Japan because it's got a French stamp."
• Must / Can't / Couldn't + Perfect Infinitive: Expressing certainty about the past. Example: "She must have been in a lot of pain."

Possibility

• Could / Might / May + Infinitive: Expresses possibility about now, the future or generally. Examples: "You should talk to your doctor first because that diet could / might / may be dangerous," "He might not / may not be a very reliable journalist."
• Could / Might / May + Perfect Infinitive: Expresses possibility about the past. Example: "That could / might / may have been the doctor who rang while we were out."

Probability

• Should / Ought to + Infinitive: Expresses probability about now, the future, or generally. Example: "You should feel better in a few days..."
• Should / Ought to + Perfect Infinitive / Was/were meant to + Infinitive: Expresses probability about the past, expected to happen. Example: "The bruise ought to have disappeared days ago."